The section of the FDA Copaxone label that specifies the average molecular weight has changed at least once since Copaxone was initially approved. The current label, effective 2/27/09, specifies a molecular-weight range of 5-9 kDa: http://www.accessdata.fda.gov/drugsatfda_docs/label/2009/020622s057lbl.pdf (see page 9 of label on page 11 of pdf file). The prior label, effective 7/12/01, specifies a molecular-weight range of 4.7-11 kDa: http://www.accessdata.fda.gov/drugsatfda_docs/label/2001/20622s15lbl.pdf (see first page of pdf file).